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  <script>
    const arr = []
    for (let index = 0; index < 100000000; index++) {
      arr[index] = new Array(1000)
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   /*  var a = {}    // count=1
  	var b = a  // count = 2
	
	  b = null   // count = 1
	  a = null  // count = 0
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    // 循环引用有问题
		// var o1= {}   //  为o1.count = 1
    // var o2 = {}   // o2.count = 1
        
    // o1.x = o2 // o2.count = 2
    // o2.y = o1 // o1.count = 2
        
    // o1 = null // o1.count = 1
    // o2 = null // o2.count = 1

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